1. Field of the Invention
The present invention relates to a wafer polishing apparatus, which polishes a wafer by a Chemical Mechanical Planarizer (CMP).
2. Description of the Related Art
In polishing by a CMP, a wafer which is rotating is pressed against a rotating polishing pad in a predetermined pressure and mechano-chemical polishing agent is supplied into a space between the polishing pad and the wafer. In this case, the wafer is pressed against the polishing pad while being held with a carrier, and the wafer receives a rotation force.
A conventional wafer polishing apparatus has three pins at the bottom of a rotating table which is connected to a drive source, and the three pins are fit into openings for the pins which are formed on the carrier, so that rotation of the driving force is transmitted to the carrier.
In fact, the wafer is generally polished at a position which is out of the center of the polishing pad; hence a friction force in side directions, acted on the wafer, affects the carrier. In the conventional wafer polishing apparatus, the force in side directions is received by the pins.
However, if the pins receive the force in side directions, polishing accuracy of the wafer deteriorates. This is because the pins receive the force while rotating and a position for receiving the force is varied, thus the carrier receives a wobbling force.
In view of the foregoing, it is an object of the present invention to provide a wafer polishing apparatus by which a wafer can be accurately manufactured.
In order to achieve the above-described object, the present invention provides a wafer polishing apparatus which polishes a surface of a wafer, comprising: a rotary shaft connected to a drive source; and a carrier that holds the wafer and presses the surface of the wafer against a polishing pad that is rotating, the carrier being connected to the rotary shaft through an Oldham""s coupling mechanism.
According to the present invention, since rotation from the rotary shaft is transmitted to the carrier through the Oldham""s coupling mechanism, the carrier can be rotated in a stable condition even though the carrier receives a force in side directions; thus the wafer can be accurately polished.
As described hereinabove, according to the present invention, the carrier can always rotate in a stable condition even though it receives a force in side directions, because the rotation from the rotary shaft is transmitted to the carrier through Oldham""s coupling mechanism. Therefore, the wafer can be accurately polished.